The invention relates to an electromagnetic torque transmitting device suitable for use as a brake or clutch, and more specifically, to an electromagnetic brake or clutch wherein a seal is utilized to isolate the working surfaces, or air gap, as well as the bearing surfaces of the device and thereby avoid foreign matter from entering said working or bearing surfaces.
Various types of electromagnetically operated brakes and clutches now in use have an operating air gap between an electromagnetic field body, which is isolated with an electrically energized coil to have magnetic flux induced therein when the coil is energized, and a magnetically retractable armature mounted for movement towards or away from the magnetic body in response to energization of the coil.
In commercial use, such as the making of string or thread on open side spinning frames in textile mills, chain driven clutches are used to receive the thread from the spinning head. Since the thread is made from cotton fiber or lint particles, the atmosphere surrounding the clutch is heavily laden with these lint particles or fibers.
Prior art clutches operating in this atmosphere have proven themselves to require a great deal of maintenance, specifically, lubrication. The lack of lubrication results in down time of the open frame spinning machine because of the total break down of the clutch. In prior art clutches the lint or foreign fibers gradually work their way into the working surfaces of the clutch and clog up the working surfaces of the air gap and interfere with the proper operation of the clutch. Further, cotton lint or foreign fibers also build up near the bearing surfaces of the output member as well as the input body and because of the nature of the foreign substance the oil is drawn out of the lubricant impregnated bearings. This results in excessive lubrication. If lubrication is lacking, the clutch bearings freeze up and demand replacement of the clutch. Obviously, this results in very high maintenance cost and excessive down time to replace the clutches in the spinning frames.